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International Journal of Marine Science 2013, Vol.3, No.14, 111-120
http://ijms.sophiapublisher.com
111
Research Report Open Access
Spatial Patterns in Diversity and Distribution of Benthic Molluscs in a Weak
Tidal Tropical Lagoon
R.E. Uwadiae
Benthic Ecology Unit, Department of Marine Sciences, University of Lagos, Akoka, Lagos, Nigeria
Corresponding author email: eferoland@yahoo.com
International Journal of Marine Science, 2013, Vol.3, No.14 doi: 10.5376/ijms.2013.03.0014
Received: 27 Feb., 2013
Accepted: 27 Mar., 2013
Published: 03 Apr., 2013
Copyright
©
2013 Uwadiae, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Uwadiae, R.E. 2013, Spatial Patterns in Diversity and Distribution of Benthic Molluscs in a Weak Tidal Tropical Lagoon, International Journal of Marine
Science, Vol.3, No.14 111
-
120 (doi: 10.5376/ijms.2013.03.0014)
Abstract
Spatial patterns in diversity and distribution of benthic molluscs in a weak tidal tropical lagoon in south-west Nigeria
were investigated from samples collected in eight study stations distributed along the stretch of the lagoon for two consecutive years.
The study also investigated selected environmental conditions of overlying water and sediment of the lagoon to establish the roles
played by environmental variables. There was a significant variation (p < 0.05) in salinity values along the study stretch which was
predicated on the existing gradient in salinity of the lagoon. Higher values of mud and Total organic content (TOC) of sediment
occurred in upstream compared to values observed in downstream stations. Mollusc communities were significantly influenced by
the spatial gradient in salinity and variability in sediment parameters. The downstream stations had brackish conditions, while the
upstream stations were typically freshwater, leading to differences in the composition and abundance of molluscs. The downstream
stations recorded higher density and diversity of mollusc compared to upstream stations. Our results suggest that benthic molluscs in
Epe Lagoon show spatial patterns related to differences in environmental parameters.
Keywords
Spatial patterns; Mollusks; Environmental variables; Weak tidal lagoon
Introduction
An evaluation of distribution patterns is the first step
to understanding the set of processes that structure
benthic communities, and thus to formulate predictive
models (Atrill, 2002). Scale-dependent patterns of
distribution may be particularly important in coastal
areas, since they are characterized by variability in
abiotic conditions (Neves et al., 2012). For benthic
fauna, patterns of distribution are related to salinity
(Atrill, 2002; Attrill and Rundle, 2002; Ysebaert et al.,
2003), sediment characteristics (Teske and Wooldridge,
2003; Anderson et al., 2004) and other factors.
Spatio-temporal variability in benthic macrofauna has
been studied in coastal aquatic systems throughout the
world (Morrisey et al., 1992; Ieno and Bastida, 1998;
Biles et al., 2003; Giberto et al., 2004). This
variability is dependent on physical and chemical
factors and biological interactions. Salinity
fluctuations in estuarine systems have a strong
influence on temporal patterns and daily and
inter-annual variations; sediment characteristics have
more influence on the spatial structure of benthic
assemblages (Neves et al., 2012).Other factors should
not be disregarded, since they can act in synergy
(Bemvenuti et al., 2005). Benthic macrofauna in
estuarine systems forms a mosaic of patches, which
are maintained by a variety of disturbances and other
biotic and abiotic factors (Morrisey et al., 1992).
Molluscs constitute one of the largest phyla of
invertebrates, in both numbers of living species and
numbers of individuals (Gomes et al., 2004). Two
classes; Gastropoda and Bivalvia are the best
represented in benthic systems, and their species have
been used to characterize benthic associations (Diaz
and Puyana, 1994).This characterization could suggest
means of sustainable exploitation and appropriate
management of commercially exploited species (Silva
et al., 2005), as well as providing important data for
biodiversity evaluations.
Nigeria is endowed with about 853 km coastline
inundated with different types of aquatic systems
which are majorly estuarine in nature. Although
several studies (Oyenekan, 1979, 1988; Oyenekan and